Train-mounted lasers blast tracks clean

Trains in the Netherlands are getting armed with lasers as part of a test to see if they can burn away dangerous material on the tracks, including autumn leaves.

Michael Franco
Freelancer Michael Franco writes about the serious and silly sides of science and technology for CNET and other pixel and paper pubs. He's kept his fingers on the keyboard while owning a B&B in Amish country, managing an eco-resort in the Caribbean, sweating in Singapore, and rehydrating (with beer, of course) in Prague. E-mail Michael.
Michael Franco
2 min read

The DM-90 train will be the first to get its leaf-zapping laser arsenal. Wikipedia/Maurits90

If you're a home owner, having a laser to vaporize all those pesky autumn leaves that cover your lawn probably sounds like a pretty good idea. Though that bit of tech isn't likely to be developed anytime soon for home use, it is being looked at as a solution for trains.

Blasting leaves from train tracks with high-powered lasers might sound like a bit of overkill, but New Scientist reports that leaves can actually form a Teflon-like coating on the tracks that make it hard for the train wheels to maintain their grip. In fact, the magazine reports that according to the UK's Network Rail, leaves on the tracks created 4.5 million hours of passenger delays in 2013.

Current track-clearing solutions include shooting either water or a gel and sand mixture called Sandite from jets mounted on the train, but they both have issues -- they need to be constantly restocked and they can erode the rails. The lasers get the job done without harming the rails "because their wavelength of 1,064 nanometers means they are absorbed by the leaves and other organic matter such as oil, but not by metal, so energy from the lasers is reflected off the rails," says New Scientist.

Dutch Railways is now conducting experiments with lasers mounted just in front of the wheels and angled down to zap away the leaves and leave the track dry, which helps with traction. The laser system was developed by researchers at Delft University of Technology (TU) along with Strukton Rail, which says (PDF) the lasers can work on trains moving at speeds of up to 80 kilometers an hour (about 50 mph).

"The question is not so much whether the laser system works, but for how long the rails will remain clean," explains TU professor Rolf Dollevoet. "We'll measure the remaining friction over time during rain, drizzle, frost and snowfall. From these measurements [we] can derive at what frequency the 6,000 kilometers of track need to be lasered and how many trains have to be equipped with lasers to achieve that."